Crossbar switch



R. P. ARTHUR CROSSBAR SWITCH Dec. 4, 1951 9 Sheets-Sheet 1 Filed Feb. 17, 1948 INVENTOR= RICHARD P. ARTHUR ATTORNEY Dec. 4, 1951 Filed Feb. 17, 1948 9 Sheets-Sheet 2 INVENTOR:

RICHARD P. ARTHUR ATTORNEY Dec. 4, 1951 R. P. ARTHUR 2,577,057

CROSSBAR SWITCH Filed Feb. 17, 1948 9 Sheets-Sheet 4- IlllIIIIIIIII/IYIII INVENTOR RICHARD P. ARTHUR I BY 4,

ATTORNEY Dec. 4, 1951 Filed Feb. 17, 1948 R. P. ARTHUR CROSSBAR SWITCH 9 SheecsSheet 5 INVENTOR RICHARD P. ARTHUR ATTORNEY Dec. 4, 1951 R. P. ARTHUR 2,577,067

CROSSBAR SWITCH Filed Feb. 17, 1948 9 Sheets-Sheet 6 FIGIB HQBA 29 loOooOooOooOo lss INSULATION F|G.|4 59 2g o O o 0 do ob e o \a 0 Q 0 56-11 FIGISB FIGJQA WOfiISO RG15 a 5615A EMA INVENTOR:

RICHARD P. ARTHUR ATTORNEY R. P. ARTHUR CROSSBAR SWITCH 9 Sheets-Sheet 7 Filed Feb. 17,1948

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INVENTOR! RICHARD P. ARTHUR ATTORNEY Dec. 4, 1951 R. P. ARTHUR 5 CROSSBAR SWITCH Filed Feb. 17,1948 7 9 Sheets-Sheet 9 I o I O O o Q O O O O Q 0 o N 0 0 m I I I I 0 E n. n n n n m n n n n n n/fi 0 o o o o o 0 o o O o o D I o o o I o 0 0I m Q 3 'l g [I 1 I m m [m m w :1 U \i! E! 2:! I2! lfil IL! Ii! I: U L

0 l I O I INVENTORS RICHARD P. ARTHUR ATTORNEY Fatented Dec. 4, 1951 2,577,067 CROSSBAR swrron Richard P. Arthur, Des Plaines, Ill., assignor to Kellogg Switchboard and Supply Company, Chicago, 111., a corporation of Illinois Application February 17, 1948, Serial No. 8,900

22 Claims. 1

This invention relates to a crossbar switch such as is used in automatic telephone systems and elsewhere. The main object of the invention is the production of a new and improved crossbar switch of simple, reliable, and economical construction.

GENERAL DESCRIPTION A crossbar switch is one having permanently paired contact members comprising sets (or stackups) arranged in intersecting rows, hereinafter respectively termed vertical rows and horizontal rows. Selecting bars (or shafts) extend along the horizontal rows to select the stackups therein. Hold bars (or armatures), extend respectively along the vertical rows to actuate, and hold, selected stackups.

In the improved construction herein disclosed, the crossbar switch includes a rectangular frame structure supporting the above-noted stackups of contacts in the form of a unitary bank built up of horizontal conducting strips and vertical conducting strips, alternating in layers to form a multi-level grid. These conducting strips are supported and insulated from each other by clamped pileups coinciding respectively with the succeeding groups of superposed vertical conducting strips. The conducting strips are so shaped and arranged that they provide the contact members of the stackups, and also constitute the required vertical and horizontal conductors multiply interconnecting such contact members. The usual applied inter-stackup wiring is thereby obviated. Moreover, this construction reduces the number of parts required to'be produced and assembled, and it makes possible the disclosed arrangement wherein one side of the contact bank is entirely unobstructed, to permit ready inspection and adjustment of the individual contact members of a stackup.

Additional features of the invention include the following:

1. The free end of each of the flexible contact springs is T-shaped. This enables a pair of contact points to be applied thereto relatively far apart, and each displaced laterally of the main spring portion. It has the advantage of enhancing direct visual inspection of the contact parts from the top of the bank, and enhancing indirect visual inspection, as through a bifurcate mirror straddling the main portion of the springs of a stackup. This construction further promotes stable twin-contact operation, since the wide spacing of the contact points insures that the spring member will twist, when necessary, to enable both contact points to engage firmly.

2. The stackup-actuating members, which respectively underlie the stackups, comprise individual pivoted levers rather than spring blades as heretofore. This construction eliminates the additional spring load heretofore imposed by the actuating springs, as Well as providing increased dimensional stability.

3. Each vertical row of stackups is provided with a common backstop rail, underlying the actuating members of the stackups. This backstop rail is adjustably supported at two points near its ends to permit it to be raised or lowered, and to be levelled, as desired, to bring the contact springs of the several stackups of the vertical row into the same normal position with respect to their fixed contact parts.

4. Each of the hold armatures (hold bars) is pivotally mounted between the front and rear rails of the switch frame. Associated adjustment facilities greatly increase permissible manufacturing tolerances by permitting the following three separate adjustments of the hold armature: (a) adjustment of one bearing location (the front one) toward and away from the contact bank to level the armature therewith, (b) adjustment of the normal, or backstop, position of the armature to a point where the several select levers carried thereon are freely movable between the armature and the actuating members which they underlie, with a minimum of lost motion upon operation of the armature, and (c) adjustment of the forward (frontstop) position of the armature to a point where any stackup to be actuated is brought to its closed position at the desired point in the travel of the armature to insure the application of the correct contact pressure.

5. The adjustment of the frontstop position of the hold armature is effected by adjusting the core of the associated electromagnet longitudinally within its relatively fixed coil, by a simple rotation of the core, which is screw-threaded in position.

6. A further feature resides in a simplified and improved V-slot centering arrangement for the selecting shafts, which permits a simple construction of the related supporting parts, and in the provision of an improved shaft-restoring spring assembly which is readily adjustable to provide the desired restoring force.

7. A still further feature relates to a new and improved arrangement especially adapted to effect stackup selection in a contact bank of the new and improved type disclosed.

Other objects and features of the invention will appear as the description progresses.

device? Figs. 1 to 19 of the accompanying drawings show a preferred embodiment of the invention, while Figs. 20 to 23 show a desirable modification of the construction of the contact bank.

Fig. 1 is a top view of the switch of Figs. 1 to 19.

Fig. 2 is a, front view of the switch installed as part of a switchboard.

Fig. 3 is a left view of the switch.

Fig. 4 is a right sectional view, taken along line 4-4 of Fig. 1.

Figs. 5 and 6 are fragmentary; top views of portions of the switch.

Fig. 7 is a left sectional view taken along line 1-1 of Fig. 6. 7

Figs. 8, 9, 10, and 11 are fragmentary front sectional views taken respectively along lines 8--8, 99, Ill-40, and IIH of Fig. 1.

Figs. 12, 13, and 151, together with their respfictivje. auxiliary views, respectively show a top clamp strip, an insulator strip, and a conducting v cal c n ac s ip use in t e se ra amp pileups of the contact bank.

Figs. 15, A, and 153 show a conducting horizontal contact strip used in the contactbank.

Figs. 16 and 17, together with their respective auxiliary views, respectively show a metal spacer and a contact spring used in the eleventh and twelfth (extension) stackups of each verticalrow of the contact bank- Fig. 18 shows a schematic view of a selectlever and associated selecting and hold mechanism.

Fig. 19 is a schematic circuit diagram of the switch of Figs. 1 to 18.

Fig. 20 is a partial top view of the switch of Figs. 1 to 19 equipped with a contact bank of similar capacity, but of modified construction.

Fig. 21 is a similar view of the same switch, but equipped with a, contact bank having no extension stackups.

Fig. 22 is an enlarged front view of the apparatus shown in Fig. 21.

Figs. 23 and 24 show the terminal-ends of partially completed conducting contact strips for use .the modified contact-bank construction.

DETAILED DESCRIPTION 'I. Consrnucrron A. The frame structure Referring generally to Fig. 1, the rectangular frame structure shown therein consists of front and rear parallel rails and 3 rigidly secured at the ends, as by welding, to end channels 2 and 4, by means of left and right-hand corner gussets 5 and 6.

The front rail 1 is an angle member. has inwardly extending top flange containing, tapped holes for receiving the screws 26 securing the front end of the bank-support :channels *25 in place. The face of thefront rail contains tapped holes and elongated openings to receivethe adjustable armature-leveling plate assemblies H2.

The rear rail upper flange contains tapped holes for receiving adjusting screws 1 l5, and screws 26 which secure the rear end of support channels 25 ;in ;place. The lower flange serves .as a mounting for hold magnets 80, and to this end it contains tapped 3 is a channel member with inwardly extending upper and lower flanges. The

holes receiving the threaded cores of such magnets. Rear rail 3 accordingly serves as a portion of the return path for the magnetic flux of the hold magnets, being of suitable magnetic material. The principal portion of rail 3 carries the rivetly attached armature bearing studs I09, as best seen in Fig. 5.

Two left-faced corner gussets 5 and two rightfaced corner gussets 5 rigidly join, as by welding, the parallel rails l and 3 to the end channels 2 and 4. One portion of each such gusset 5 and B is flanged inwardly to provide a mounting space for shaft brackets 18 and I9, see Fig. 1.

Figs. 6 and 7 show an intermediate cross brace l, of channel construction with upper and lower legs. Sufficient of .each leg portion, at the ends, is cut away to permit the ends of the web to be bent for attachment, by screws 8, to the front and rear rails l and 3. Brace 1 serves to strengthen the frame structure and to support the selecting slia ftguide rail l3.

The shaft guide rail It comprises a plate-like member with turned flanged tabs containing slotted openings for securing the guide rail 3 to the lower leg of brace I, by means of screws [4. The upper portion of shaft guide rail l3 contains accurately sized and spaced notches to freely receive the tubular portions 50 of thesix selecting shafts, such as S???- for support and alignment.

B. The mounting rollers rr n t F 1 a d m un ng ll rs I a e at ac ed to end cha el i nd 4 b means of roller studs H. As seen in Fig], wherein the switch is shown mounted in a suitable switchboard frame (fragmentarily shown), rollers iii are arranged to lie within the guide assembly l2, which is slidingly secured to the mounting frame, to permit the switch to be moved inwardly and outwardly (partly as a rolling action, and partly as a sliding action) in the manner of a drawer in steel cabinets of usual construction.

0. The Zeg:bm'ls pai o l ba s 5 unde i h fra e t ture. .One such leg bail I5 is shown in Figs. 2 and 3. As shown therein, the leg bail i5 is attached to therearface of front parallel mounting rail .1 by means of screws L6, and is attached t e l e a e f rear parafle lmiin rail 3 by means of screw 11. The bails serve as up gsdurin a m ly. wi in and a ustment of the switch. They also may be used to add rigidity to the frame structure; support legs of cable wiring (not shown).

D. The shaft brackets Two shaft brackets i3 and I9, extendingacross thefraine structure, are shown in Figs. 1 tov 4. Each such shaft bracketconsists of an upstandins main-p r onand a o ta p on fla ged outwardly. The/main no t ono each ilq 'shaf bracket 18 and i9 is secured at the ends to corner gussets 5 and 6, by means of screws Zil. The upstanding portion of brackets [8 and't 9 supports the select'shafts, the shaft centerin'g assem i sandthe assembl esofpfbnorina rqntacts. Three upwardly extending tabs 62' are integrally formed with each shaft bracket to serve as auxiliary adjustment supports for the shaftcentering means. 7

T fian e nortionor the haft r ket Q Q' tains tapped holes to threadedly receive the cores of the select magnets for supporting and.

E. The support channels The support channels 25 consist of a top web portion, as shown in Fig. 5, with left and right leg portions extending downwardly, as viewed in cross section in Figs. 8, 9, 10, and 11. The end portions of the legs are cut away for suitably securing the web portions to the upper flanges of the parallel mounting rails l and 3, by means of screws 25. The holes in the web portion, through which screws 26 pass, are elongated to permit desired adjustments in the positioning of support channels 25. See Fig. 1.

Thetop web portion, as shown in Fig. 5, supports the stackups of contacts and the hold pilot assembly, and is provided with tapped holes 21 and 28 for this purpose. Apertures 29 are also provided in the web portion for holding dowel pins used only in aligning the stackups during assembly.

The web portion and right leg of support channel 25 contains slotted openings for pivotally mounting the actuating tabs 33, and the right leg contains tapped holes for receiving the back-stop rail supporting screws 30.

F. The back-stop rails The backstop rails 32, as shown in Fig. 5, comprise narrow flat plate-like members, vertically extending across the frame structure, with the flat sides paralleling the right legs of the support channels 25. The top edge is notched to readily receive the depressed portion of the actuating tabs 33, and the flat portion contains elongated openings for the passing of backstop rail supporting screws 30.

The backstop rails 32 are secured to the right leg portions of support channels 25 by screws 38, and maintained in proper position by means of spacers SE. The elongated apertures in guide rails 32, through which screws 30 pass, permit the guide rails 32 to be adjusted upwardly or downwardly as is required for positioning the actuating tabs 33.

The backstop rails 32 serve as a positioning support member and as an adjustable backstop for the front portions of the actuating tabs 33. The adjustable backstop rails further serve to properly position the spring contacts 15! and I'll of the stackup, in relation to their fixed contact members I57, as will be subsequently disclosed.

G. The actuating tabs The actuating tabs 33, one of which is shown in Fig. 18, comprise generally a flat top portion and a downwardly extending flanged portion. The top portion of each tab 33 is notched on each edge near the end for pivotally mounting the tab in the apertures provided for in the support channels 25. See Fig. 5.

The top portion of actuating tab 33 is depressed near the front to provide a socket for the stackup lifter studs I65, etc. The downwardly protruding depressed portion, lies within the notched portions of the backstop rails 32. to permit the front top portion of the actuating tabs 33 to lie flat upon the backstop rail 32 during inactuated periods.

The actuating tabs 33 are positioned by the adjustable backstop rails 32, one such rail positionally supporting all the actuating tabsv 33 underlying each vertical group of stackups com-' prising a contact bank I50.

The adjustably mounted armature 98, support-- ing the selecting levers I25, may be upwardly or downwardly adjusted for clearance, sufiicient to permit the selecting levers I25 to assume their alternate selective positions underlying the edge of the downwardly extending flanged portion of the actuating tabs 33, in response to the action of the selecting mechanism for stackup actuation.

H. The selecting shafts The six selecting shafts SI2, S34, S5-6, S'i8, S9-l0, and S|ll2, shown in Fig. 1, are all of similar construction; a side view of shaft Si2 being shown in Fig. 2. Each such shaft comprises essentially a metal tube 40, having integrally-formed finger guides I35 (see Fig. 18), through which the selective action of the shaft is performed incidental to the rotation of the shaft about its longitudinal axis.

As shown in Fig. 2, bearing rod 53, composed of suitable bearing material, is inserted in the hollow portion of shaft 43 at one end, and retained in position by a rivet M. The end portion of rod 43 is cupped to receive the supporting spherical smooth end portion of an adjustable bearing screw :25. The body of the screw 45 is threaded into its tapped hole in shaft bracket I9, with sufficient of the slotted head portion extending through the shaft bracket it to permit screw driver adjustment. Screw d5 serves as an adjustment means for the regulation of any shaft end play. The screw 45 is provided with a locking hexagonal nut 48 to lock the screw in a desired position. This arrangement is advantageous in that the selecting shaft can be adjusted to turn freely with a minimum amount of friction and to compensate for any slight differences in shaft lengths occurring in construction. Further, the selecting shafts are readily mountable and demountable.

As previously described, a selecting shaft guide rail [3 may be provided in switches using long selecting shafts to support the shafts at the center and to prevent damage to such rods, as a result of improper handling. See Fig. 7. The rails [3 give greater stability to the frame structure and to the selecting shafts, prevent side to side deviation, and assist in keeping the shafts in proper alignment.

The other ends of the selecting shafts are supported in the following manner. An armature-bearing block 48, composed of suitable hearing material, has an inner cylindrical end portion inserted in the hollow end portion of rod 49 and is secured in position by a rivet 41'. The outer end portion of block 46 is turned to form a collar section of reduced diameter to reduce friction between the bearing block and the shaft bracket [8. The collar section is turned to form a bearing pin of smaller diameter for insertion in a smooth hole drilled in shaft bracket [8, to permit the shaft rods Sl-2, etc. to turn freely in response to the selective action of select magnets Ml, M2, etc.

It will be observed that the first, third, and fifth of the selecting shafts of a group are all assembled in the same manner with the armature 5! thereof at the left of the frame structure, as viewed in Fig. 1, while the second, fourth, and sixth are assembled in reverse position, the armatures of the latter being at the right. Ac-

armors 7 drdingly, the magnets M1 and M2, M5 and M6, and M9 and Mill), for the first, third; and. fifth shafts, are located on the leftshaft. bracket. t8, while the magnets M3 and. M4,. Ml. and M8, and M l'l and MLZ', for the. second,'fourth,. and sixth shaftsare locatedon the rightshaft bracket IQ.

Armaturesv 5i are provided-for the select shafts as shown in Figs. 2' to. 4. Each compriseaplatelike main tractive portion, and; an integrallyformed offset portion. which is secured to themder side.- of armatureebearin'g block 46, by; the riveted lower extending portion of roller stud. 1.8- and by rivet: 5.4.

Armature has a pair of wing portions 52 and 53 formed integrally therewith and arranged tobe acted. upon by the respective select magnets MI and M2. The normal relationship between wings 52, and 53 of any shaft and the associated select magnets (such as M! and M2) is illustrated in Fig. 3. g

The offset armature, 51 is so placed with reference to shaft brackets iii or !9, that in attracted position. only a very narrow gap exists between the backportion of, the armature and the shaft bracket. Thus,- when one of the. magnets, such as MI or M2; (seeFig. 2), is energized, the magnetic flux passesv from the front end of the magnet to the associated wing (52, or 53) of the concernedarmaturejl, whence it traverses the small air gap between the back portion of armatures 5! and the shaft bracket 8.0r i9), and returns through the shaft bracket to the rear end. of the. energized magnet. The concerned armature wing 52 M53 is thereby attracted into engagement with the energized magnet, causing rotation, of the concerned selecting shaft in one direction or another. It will be notedth-at the armature 5! is offset, to avoid thenecessity of cutting away portions of the shaft brackets Sand 89, and is so designed that each wing 52 or 53 in attracted position lies flatly upon the front core ofthe selecting magnetsMl, etc. for increased contact surface.

The front stop position. of armature wings 52 or 53 is adjustable by adjusting the select-magnet (Ml, M2, etc.) cores longitudinally. As shown in Fig. 3, the coreof each of such magnet, M! and M2, etc, is threaded in the flange of bracket It or [9; is locked in position by retaining nut. 2 1.; and is arranged to. turnireelywithin its coil to provide adjustment of thestrokeof armature 5 I.

I. The shaft positioning assembly A shaft positioning assembly is proyidedto returngthe selecting -shafts.Sl-2, etc., to their normal (unopera-ted) position after the selectiveeace tion-of such shafts has beencompleted; Such an assembly, asshowninFiigs. 2 and 4; consists essentially of an adjustable support bracketed, a cam spring, 55 and'cam member. 63-, and cooperates: with ashaft rollers?) and stud, E99.

Each of the shaft brackets i3: and :9- has three offset support-bracketses (Fig. 2). The lower end of each is secured to its shaft bracket 5-8 or N by rivetsti, the'upper, inwardly ofiset, portion is adjustably secured to a verticaltab 62 by means of interlockingfadjustment screws; comprising pull-in screw 6% and DUSIIrOllt'SClGVZ 63, through which it may bereadily bent toward or away from its shaftbracket and-locked in posi tion with both screws. tight:

Screw 53 passes through a clearance hole in bracket 66'; and is threadedly received within a tapped hole in its mounting tab; 62. When screw $3 tightened, .itshead pulls. the oflsetgportion of: the. bracket. 60 inwardly: with. respect to. shaft; bracket.-.l&..or 19V to astop position, determined bythecurrentsetting of screw 694..v

The. adjusting; setscrew .64 is, threaded into a,

1 tapped hole in the ofiset portion of. bracket 60..

and its rounded front end portion bears against the shaft bracket (IBor' I9); Thus, by tightening screw- 643, the. end; portionv of such. screw pushes against the shaftbracket (i801; l9) to move the upper ofiset portioncf bracket 60 outwardly from such bracket is or l9. Thus, the opposed-drive, adjusting screws 63 and B4,, acting together, result in a push-pull interlocking adjustment means for the support bracket 56;.

The adjustable support brackets 5t carry the. cam springs. 65 and the; shaft off-normal springcontacts 15, such cam springs 65 and spring contacts l5 and their associated spacing and insulating washers, beingsecured thereto by screws 68.

The cam spring 65 comprises a flat plate of spring steel, secured at the top to thefiat offset portion of bracket 50,,by means of. screws 63. See Figs. 2 and 4. The downwardly-extending lower portion is secured to the cam member 55-, by means of rivets 67. The cam member 65 comprises, in general, aplate-like structure formed with a V-notched cam portion at the lower end to engage. the shaft positioningrollers 69. The. cam members 56 are maintained in a. properlytensioned engagement with rollers 59, by means of the attachedcam spring 65=wl 1ich is secured to the adjustable support bracket 6E3. Thus, the previously-described adjustment of the support bracket 68 increases or decreases the tension of cam, spring 65 and, consequently, the tension existing between the surfaceof the V-shaped portion of the cam. member 65 and the engaged roller 6%.

The selecting shaft positioning rollers (59' are arranged to lie within the centering V-shaped notched portion of cam member 66,. and are mounted upon roller stud '19. The upper portion of roller Stud 70. has. a bearing shoulder upon which roller 69. is maintained in position. The. upper, portion of rollerstud if] is turned to form a supportingv axle, upon which roller revolves. The roller 69 is provided, with a bearing washer H to reduce friction at the end, and both roller 69'and washer ll aresecured in position by the rivetedupper end portion of stud it.

The extended lower portion of studliiextends through an aperture-in select-shaft armature bearing block 46, and err-through an aperture in the offset arm of armature SLandisrigidly securedin placeby riveting the lower end of such stud.

It will be noted at this point that, as a selecting shaft such as Sl-2" is rotated in one direction or the otherin response to the energization of one'of the otherof select magnets Mi or M2, the, shaft. roller stud. it. moves in the same direction. Theroller 69 then leaves the. center of the V notch in cam member. 66, and moves toward the inclined, sides, of the notch. and, in so doing, extendsthe cammember 56, back further against. the tensioned. cam spring 65. Immediately upon deenergization of. the

elect magnet, the tension ofthe V slot cam portion 50 engaging, the. roller forces the roller to resume its center positionin. the V-- shaped positioning notch. Consequently, the selecting-shaft associated with. such roller and stud resumes its normal position.

The. shaft off-normal springs 75 aresecured to support bracket 69 by means of screws I59. The cam member 99 carries an insulating stud I6 that acts upon the adjacent spring contact of springs I to cause the springs to make electrical contact with each other When the came member 66 is pushed inwardly incidental to the rotation of the associated select shaft SI-2. The shaft off-normal springs may thus be used for pilot purposes, to indicate to a control circuit that a shaft has been moved into a selecting position.

J. The armature and hold magnet A hold magnet 89 and armature 99 is provided for each vertical row of stackups to operate selected stackups of contacts therein, and a 'stackup of hold-pilot contacts.

The hold magnets 89 are adjustably mounted, as shown in Fig. 2, upon the lower flanged portion of the rear mounting rail 3, below and slightly to the left of their associated vertical row of stackups. Each magnet 99 includes an energizin solenoid coil on a cylindrical magnetic core. Each such core passes through its coil, and has its upper end 8| increased in diameter (by knurling) to retain the coil in place, and has its lower end 82 threaded and end-slotted for mounting as a screw.

The coils of magnets 89 are provided with terminals 83 for external connections. An insulating collar 84- encircles the core between the rear spool head 85 and rail 3 to maintain the base portion of terminals 83 out of contact with rail 3. Rear spool heads 86 is square, wherefore it bears against the web portion of rail 3 to prevent the coil from turning.

The end portion 82 is threaded into a tapped aperture in the lower flange of rail 3 for supporting and longitudinally adjusting the position of magnets 89 to adjust the front stop position of armature 99. The slotted portions of threaded ends 82 are provided to facilitate adjustment, and a common hexagonal nut 81 is provided to lock the core in place after proper adjustment is made.

A hold-magnet armature 99 underlies each vertical row of stackups. Each is pivotally tmounted at each end. A plan view of one such armature 99 is shownin Fig. 5, and cross. sectional views are shown in Figs. 9 and 11.

Referring now particularly to Fig. 5, the armature 99 shown therein extends from rear rail 3 to front rail I, being pivoted at each. It comprises two principal portions, formed integrally with each other, a tractive portion 9I which operatively overlies the upper end of the core of its corresponding hold magnet 89, and a laterally extending (main) portion 92 which underlies the associated row of stackups.

Armature 99 has a vertical mounting tab 93 at each end for pivotally mounting the armature on bearing pins I99 and I I9, secured to the front and rear rails 3 and I.

Portion 92 has an upwardly extending flange 94 containing six pairs of narrow slots 95. One such pair is. shown in Fig. 18. The portion of flange 99 between the slots 95 of each pair serves as a pivot mounting for a select lever I25.

A tab-like upwardly offset portion I9l of armature 99 serves to actuate the associated hold-pilot contacts when the armature is operated. The hold-pilot assembly (as shown in Fig. 8) contains an armature returning spring H3 that serves to retain armature 99 to its illustrated normal position.

The main portion 92 of armature 99 has three integrally-formed support arms 99 to which a channel-shaped actuating bar 97 is rigidly secured, as by riveting.

A cross-sectional view of the actuating bar 9'! (fragmentarily shown in perspective in Fig. 18) is shown in Figs. 9 and 11, and a top view is shown in Fig. 5. Bar 91 has a relatively short. inner leg 99 acting as an intermediate support for the, select levers I25, and a taller outer leg 98 which has six wide slots I99 for guidingly receiving select fingers I25. Each slot I99 is opposed in position to one of the pairs of slots in flange 94 of armature 99 as shown best in Fig. 18.

The three holes appearing in the main portion 92 of armature 99 in Fig. 5 are used only during the formative period as pilot holes.

A residual clip II! is provided, as shown in Fig. 18, and is attached to the tractive portion SI of armature 99 to eliminate any undesirable residual magnetism. Referring now to Figs. 2 and 5, the magnetic return path for the hold magnets 99 will be described. Upon energization of one of the hold magnets 89, the magnetic flux passes from the front end of the magnet core to the tractive portion 9| of the concerned armature 99 and to the vertical mounting tab 99, whence it traverses the small air gap existing between tab 93 and rear rail 3, and returns through the rail 3 to the rear end of the energized magnet. The concerned tractive portion 9I is thereby attracted into engagement with the energized magnet, causing the actuating portion of armature 99 to operate.

The front stop of the armature 99 is regulated by the longitudinal adjustment of the hold magnets 89, as heretofore described, and the backstop is regulated as shown in Fig. 2 by an adjustable regulating backstop screw I I5 which is threaded through the upper flange portion of rear rail 3 for engagement with the tractive portion 9| of armature 99, and is secured in position after adjustment by lock nut I I9.

' mounted at either end. As shown in Fig.5, the

rear end of armature 99 is supported by a bearing stud I99 which is secured by rivetin to the web portion of rear mounting rail 3. Bearing stud I99 has an inner bearing shoulder of a diameter sufiiciently large to retain the bearin in place on the inner surface of rail 3. The smaller body portion of such bearing stud I99 passes through an aperture in rail 3 and is secured in place by riveting at its outer end. The inner end portion of stud I99 is turned to form a bearing pin, of a diameter less than that of the hearing shoulder, for insertion in a hole of slightly larger diameter in the upstanding pivot tab 93 of armature 99, to form a simple thrust bearing.

The other (front) end of armature 99 is pivotally mounted on an outboard bearing pin H9, as shown in Figs. 2 and 5. The body portion of the outboard bearin pin H9 passes through an elongated opening III (see Fig. 2) in the face of the front mounting rail I, which is provided for armature leveling means. The inner portion of bearing H9 is turned to form a bearing shoulder of smaller diameter to reduce the friction between the shoulder and the outer face of the armature pivot tab 93 which is thrust against it. The bearing pin H9 is further turned to a diameter smaller than that of the bearing shoulder for insertion into an aperture provided in the armature pivot tab 93, which is of slightly larger diameter, to permit the armature to pivot freely about such pin Its. By this arrangement, a simple thrust bearing is provided similar to the bearing I33 which supports the other end of the armature "93, with the exception that *the outer terminating end of the outboard bearing H3 is not secured to the frame structure, as

was pin 139, but is secured as 'by-rivetinggthrough an aperture contained in the upper portion of armature leveling plate H2. See Fig. 2.

As previously described, and as shown in Fig. 2, the outboard bearing pin IIB, pivotally supporting armature 30, passes through an elongated aperture III in the face of rail I and is secured to the upper portion of armature-leveling plate I I2. Plate I I'Z contains an elongated aperture ll' directly below the opening receivingbearing pin IIB, through which screw H3 it passes and is threaded into rail I, toadjustably secure plate Hi! to "the outside face of :rail I. Byloosening screw H3, plate IjI'Z can .be raised and lowered, because of the elongated aperture "I I4 therein contained through which screw I I3-pass es; and the attached outboard bearing I 5 3 is consequently raised and lowered in the elongated aperture III in .rail I, through which it passes; to a'djustably level the armature '90 in a desired position where 'it'may be L. The selecting mechanism A'selectinglever I is provided for each pair of stackups in the switch and in its normal (unoperated) condition occupies a position midway between and below the pair of stackups. Figs.

. '2, 9, and 11 represent a side view of the levers 125, and show the relationship existing between such levers and a stackup-actuating tab .A top view of the .six levers I25, vertically positioned with respect to the stackup-actuating tabs 33 of the'adj'oining bank, is shown in Fig. 5.

Referringparticularly now to the pictorial view I8,wherein one such lever I25 isshown to co 1.- prise generally va. hairpin-like structure lying in a horizontal plane, the lever I25 is composed of one piece of spring material and has onesquare shaped end with parallel oifset sides IN. The ofiset.side portions I211 areguided and supported within the slots I in the .front leg portion 33 ofactuatingehannel bar-91 and are intermediately supported by the .upper edge of the .rearileg 99 .ofbarll'l.

The mid-section I 26 of lever I25 consists of two :parallel portions which are pinched together near the ends .and terminate in open endportions I29 which are formed in semi-circular fashion to form bearing surfaces. The end portions I29 are pivotally secured by their inherent tension to the intermediate bearing I33 formed between each 12 pair of..slots in theflange portion 94 ofarmature 90.

The slots {I33 serve to guide the side portions I23 of the-selecting levers I25 into their respective selecting positions under their associated stackup actuating tabs 33 for stackup selection incidental to the rotations of the selecting shafts SI--2 'toSI II2.

Themethod :of mounting selecting levers I25, as herein disclosed, provides a ready method for installing and removing such levers.

Each selecting lever I25 is movedfrom its normal position to one of the other of its selecting positions by the positive action of a finger spring :I 33 acting in response to-selectingshaft rotation.

The finger spring 1-36, as shown in Fig. 18, comprises generally a vertically extending hairpinshaped member'constructed of a single piece of spring material shaped to form aloop I3I at one end and having two vertically extending driving arms I32 terminating in outwardly turned end portions I33. I

As shown in Fig. '18,, the end portions I33 are outwardly turned for ease in assembly when spring I30 is inserted into position. Arms I 32, between which midportion I23 of the associated selecting lever I25 lies, serve as a yielding drive :means effectiv todrive the associated select lever, unless retained,into any one of its three'positions (the illustrated normal position, its frontselect position, and its rear selectposition), in response to the rotation of its "selecting shaft in the corresponding direction.

Arms I32 are driven by neck portion I40 of finger guide I35, against which they are inwardly tensioned. These arms are contained within guide channels between parts I31 and I38. Either finger I32 moves along its guide channel, away from neck portion M3, incidental to its select lever being'restrained from following rotation of the shaft.

Loop portion I3I of springs I30 rests upon the top surface of its select shaft, such as S! I-I2 in Fig. 18, and is retained somewhat loosely in position by tabs I 3-3. Accordingly, the matched tension of "the driving arms I32 of finger spring provides for afollowing action of one such arm when the other arm is driven in response to the movement of finger guide I35, wherefore both arms act together as one long spring.

.Each finger guide I35 .has wing portions I36 which are received within slots in the upper portion of its selecting shaft, such as SI II2. The lower end portion of part I35 extends through a suitable'opening in the shaft, and is riveted over on the bottom to hold it securely in place.

It will be noted, in view of the foregoing, that the spring I 33 is readily inserted withinthe structure and is easily removable by spreading the side arms I32 to a distance wider than the supporting plate I31 and laying the spring backwards until it can be slipped off the lower part of guide I35, a mere reversal of the assembly steps.

M. Bank construction Referring now particularly to Figs. 1, 2 and 8 to 17, the construction of the contact bank of the switch, supported on the switch frame on channels 25 to provide the vertical and horizontal rows of selectively operable stackups of contact members, will be discussed more in detail. The term vertical is employed in connection with the rows of stackups in the contact bank to refer to a direction across the frame, in contrast with the 13 term horizontal, employed to refer 'to a direction along the frame.

Each vertical row of stackups comprises ten principal stackups (the first ten, counting from front rail) and two extension stackups (the eleventh and twelfth). In the disclosed arrangement, each principal stackup (see Fig. 11) has six contact pairs. Functionally, they comprise an upper group of three, and a lower group of three contact pairs. Each extension stackup (see Figs. 9 and 10) comprises but three contact pairs, related specifically to the up er, or the lower, group Of contact pairs in the same vertical row.

The contact bank comprises a unitary structure in that the vertical and horizontal conducting strips I55 and I50, assembled together to provide the stackups, extend entirely through the bank in the respective intersecting directions. Such strips alternate in layers, and are maintained in assembled position by clamping pileups I50, one for each support channel 25. Fig. 1 shows a top view of the first three clamping pileups I 55, and the last.

As shown best in Figs. 9 to 11, each clamping pileup I55 comprises layers of conducting members, interspersed with separating insulator strips I54, clamped between an upper clamp strip I5! and a cross-support channel 25, by screws I 53 which pass through the pileup.

Each clamping pileup I56], except the starting one (at the left of the switch), includes six conducting strips I56 common to the stackups comprising the vertical row immediately to the left. Such strips serve as a common multiple for the fixed contact members of all stackups in that vertical row, for the leftwardly overhanging edge portions of the conducting strips I55 comprise the fixed contact members in question. More particularly, each conducting strip I55 is wider than the insulator strips I54, and has a free edge portion extending to the left of the clamping pileup to serve as fixed-contact locations in the concerned vertical row of stackups. Each such strip I 55 has a row of contact points I58 (Fig.

14B) fixed to the lower side of the overhanging left edge portion for cooperation, in pairs, with flexible travelling contact springs, I5I or i'II. The overhanging edge portion of each strip I55 is notched between contact points I 58 to admit more light to the zone Of the contact points, and to permit a more direct view of the underlying contact springs, leaving unnotched portions I51, Figs. 14 and 1413.

Figs. 12, 13, and 14 show clearance holes I52 and I55, in clamp plate l5I and. in insulators I54, for screws 55, and enlarged clearance holes !59 in conducting strips I55 for these screws. The small holes 29, shown in Figs. 5 and 14 to 17, are pilot holes which may be used during assembly of the bank for alignment of the parts, on guide pins which may be later withdrawn from underneath, as the clamp plates l5I are tightened in place- 4 As seen best by a comparison of Fig. 1 with Figs. 9'to-11, each clamping pileup I50, preceding the last (to the right), clampingly supports the base portion of the flexible travelling contact springs (I6I, H!) of the twelve stackups comprising the vertical row lying immediately to the right of such clamping pileup. There are six such springs .I5I for each of the ten principal stackups in a vertical row, and three such springs HI for each of the two extension stackups (eleventh and twelfth) in a vertical row. Any such contact spring (I BI, I'II) extends to the right to the vicinity of the next succeeding clampingpileup I50, with its free end cooperatively underlying the overhanging left edge portion of the asso ciated vertical multiple strip, secured in the next succeeding clamping pileup.

It will be observed that two clamping pileups are required for the first vertical row of stackups, the first to support the base portion of the flexible contact springs, the second to support the vertical conducting strips comprising the fixed contact members of the vertical row of stackups. For each vertical row of stackups succeeding the first, only a single clamping pileup is required. Each clamping pileup between the first and the last supports contact elements for two vertical rows of stackups-fixed contact elements for the immediately preceding vertical row, and travelling spring contact elements for the immediately succeeding vertical row of stackups.

In any horizontal row of principal stackups (rows I to II counting from the front of the switch), the six springs I M of any stackup are attached integrally to respective horizontal conducting strips I 56 clamped together in superposed relationship in all clamping pileups I 50.

Figs. 15, A, and 153 show a horizontal multiple strip I adapted for use in any odd-numbered horizontal row of principal stackups in the contact bank. Strip 565 has the previouslymentioned pilot holes 29 for receiving locating pins extending through the clamping pileups during assembly of the bank. The arcuate portions cut from the left edge of the strip at each point I63 provide lateral clearance from th clamping screws 555. The springs IEI are formed from the material comprising the strip by blanking away metal according to the preferred outline form of the springs, leaving a connecting portion I62 intact alongside each spring I6I. Leaving the springs I 5| attached in a continuous horizontal strip, besides rendering it unnecessary to provide a separate horizontal multiple conductor, greatly reduces the handling of flexible spring parts before during the final bank-assembly operation, and before, as well as greatly en'- hancing the alignment of springs I5I in the bank. Similar considerations apply to the fixed contact parts formed integrally with the vertical conducting strips.

Each horizontal conducting strip I55 has pairs of contact points I54 affixed to the upper side of the contact springs i6! thereof in a position to mate with the pairs of contact points 1'58 dependingly secured to vertical strips I 55. Additionally, each strip I 55 has an overlying terminal member .IiEi fixed therewith at the starting end (the left end when assembled in the contact bank of the switch). Part I'Iil serves to provide a rigid terminal to which an external conductor can be attached, and serves, further, to maintain the desired spacing of the horizontal strips I55 and attached flexible springs Hii in the starting pileup I55, which lacks the vertical conducting strips I 55 of the succeeding pileups 555. For this purpose, each terminal member Iifl is preferably of the same thickness or material as the vertical conducting strips I 56. 9 I

As indicated in Fig. 1, there are two columns of terminal members I for each horizontal row of staokups in the contact bank. In the preferred arrangement, strip I55, specifically as shown in Fig. 15, is employed for the first, third, and fifth overlying strips. For the second, fourth, and sixth strips in the overlying assembly, the 'rearwardly extending terminal portion of part 15 I is preferably shifted to a point near the rear edge of strip IBB. This arrangement, it will be understood, relates merely to separating the terminal points laterally to facilitate identifying them and attaching the external conductors thereto.

Considering the strips 168 as used in the evennumbered horizontal rows of principal stackups, the same blanked form is used, but turned over to place connecting portions I62 and cutout portions I63 to the front of the strip, in agreement with the showing in Fig. 1. With the blank thus turned, contact points I64 and terminal member 110 are applied to the top to form a complete strip similar to that as shown specifically in Fig. 15, but comprising a mirror image thereof.

Inthe specific form of the invention illustrated in Figs. 1 to 1-9, wherein extension stackups ii and I2 are employed for each vertical row to double the selective capacity of the ten principal stackups therein (increase it from ten to twenty), the vertical conducting strips I 56'do not have external conductors connected directly thereto,

as do the horizontal con-ducting strips 166, for the external connections are made to the vertical conducting strips of any vertical row of stackups through the alternatively operable eleventh and twelfth (extension) stackups of the vertical row. Accordingly, the contact springs 21! of any extension stackup represent individual contact springs, not mu'ltipled with the contact springs in the extension stackups lying in other vertical rows. Each contact spring I1I in an extension stackup has the construction shown in Figs. 1'7, 17A, and .17 B.

As shown in Fig. 10, the contact springs I1! in any stackup of the eleventh horizontal row in the contact bank (the first extension stackup in each vertical row) occupy the upper three travelling-spring positions in the stackup for cooperation respectively with the upper three vertical conducting. strips I55 in the next succeeding clamping pileup I50. As shown in Fig.9, the contactrspr'ings I1I in any stackup of the twelfth horizontal row of the contact bank (the second extension 'stackup in any vertical .row) lie in the lower three travelling spring positions in the stackup for cooperation with the lower three vertical conducting strips 56 in the next succeeding clamping pileup I50.

Contact spring I11, as shown in Fig. 17, with the contact points afiixed to the upper side thereof, is suitable for use in the eleventh stackup in any'vertical row. The pierced,.forwardly extending tab portion I13 is adapted to serve as a terminal point for the connection of external conductors generally according to the circuit diagram shown in Fig. 19. Parts 113, for any stack up in the eleventh horizontal row, overlie the contact springs in the twelfth row of stackups.

For use in the twelfth horizontal row of stackups, part HI as shown in Figs. 1'1, 17A, and 17B, is turned over before the contact points are fixed thereto, to bring terminal portion I13 to the front and :spring portion Hi to the rear. Contact points are then fixed to the top side of the part in its turned over position to provide a part which is a mirror image of that shown in Fig. 11. Accordingly, the terminal portions I13 for any stackup in the twelfth horizontal row underlie the contact springs in the eleventh horizontal row of stackups.

It is contemplated that the three local conductors 202 (Fig-1'9) for each vertical row of stackups will be installed incidental to-contactbank assembly to interconnect the terminal tabs N3 of the eleventh stackup therein respectively with terminal tabs I13 of the associated twelfth stackup. Conductors 2E2 are omitted from the structural views merely to simplify the drawings. During the wiring operation, the three external conductors related to the two extension stackups in the same vertical row are readily attached to the terminal tabs N3 of the eleventh stackup, which overlie the contact springs in the associated twelfth stackup.

In any intermediate clamping pileup I50, spring members HI, being of the same thickness of material as horizontal conducting strips I60, fit into the clamping pileup without special adaptation. In the first clamping pileup I50, the base portion of each spring member MI is overlaid with a spacer I16 of a thickness to match that of the terminal members 119 secured to the starting end of horizontal strips I69 in the first ten horizontal rows. In the final clamping pileup I59, the space opposite each spring member I11 in the eleventh and twelfth horizontal .rows is occupied by a spacer strip I89, Figs 9 and 10, of the same thickness as springs I1] strips I60.

N. Stackup actuation Actuation of any stackup of the contact bank is effected by flexing the travelling springs thereof upwardly into engagement with their associated fixed contacts. For this purpose, each such stackup is provided with an actuating stud I65 or lit, shown best in Figs. 9 to ll. Actuating studs I65 are employed respectively for the stack ups in the first eleven horizontal .rows, while shorter studs I14 are employed for the stacku-ps in the twelfth (second extension) horizontal row. Each such stud extends through an intermediate portion of the flexible travelling springs of its stackup, and has a step-like lifting portion extending forward at each spring level. Preferably, each contact spring is lightly tensioned downwardly against its lifting portion of the stud.

As shown best in Figs. 15 and 1'1, each spring IEiI or I11 has a stud-receiving slot which Sis sufiici'ently elongated that an actuating stud I55 or I14 can be passed therethrough endwise. lhese studs are conveniently assembled with its stackup by passing it downward through the slots in the springs from above the contact bank after the latter is otherwise completely assembled. With the foot of the stud resting against its actuating tab somewhat to the rear of its illustrated position, the mid portion of all the springs of the stackup may be flexed upwardly, as by a suitable notched tool, sufficiently to permit the stud to be moved bodily forward to its illustrated effective position. When the contact springs are then released, they rest on their respective step portions to hold the foot of the stud in its "socket in the underlying part 33. The top of the stud has a forward raised portion which enters a small opening forward of stud-receiving opening to hold the top of the ladder in its illustrated forward-position. When desired, a stud IE5 or 114 may be removed by a reversal of the described assembly operation.

When an actauting tab 33 israised, incidental to its underlying armature 9d operating when the concerned select lever 525 has been brought underneath such tab 33 by a stackup-selecting operation, the actu'a'titng stud IE5 or I15 resting thereon is lifted to flex its travelling springs IN or I1I upwardly until the contact points of each spring engage those of its corresponding vertical conducting strip I56. Any further upward movement (over-travel) of the actuating stud causes O. Stackup inspection and adiustment As is more or less apparent from the foregoing, one design aim has been to provide parts which, when assembled to form the illustrated contact bank, will function substantially as intended without requiring adjustment manipulations within the contact bank itself, except for any contact spring found to be slightly deformed (such as being bowed or twisted). To this end, the actuating-stud location is placed a substantial distance from the free end of contact springs IGI or I'll, wherefore a rather generous overtravel movement of an actuating stud is required to build up a specified contact pressure. Accordingly, normal slight dimensional variations in pileup heights, in the heights of the contact points applied to parts I56, IESI, and I'll, and in the straightness of the parts, will cause but relatively small proportional variations in contact pressure among the contact pairs in a stackup, and from stackup to stackup in a vertical row.

A further design aim has been to so relate the parts that the point in armature travel at which any contact spring engages its fixed contact points may be directly observed; that all contact points of a stackup may be brought into view, at the same time, at least indirectly, as through a suitable mirror; and that any contact spring found to be sufiiciently deformed that it does not engage one, or both, of its fixed contacts at substantially the desired point in armature travel may be readily adjusted until it does so.

Since the free end of each contact spring I BI or I 'II is T-shaped, the action of the free end of the contact springs of a stackup may be directly observed by looking downwardly, and to the right, into the contact bank along both sides of the contact springs of the stackup as both ends of the crosshead of each such spring are then directly in view. When all contact springs engage at the same point in the armature travel, the free'ends of all springs may be observed to stop at the same time. If one spring be seen to stop substantially before, or after, the others, a deformity is indicated, which may be compensated for by bending the spring up or down, as required. Such bending is preferably done at, or just forward of, the portion engaged by the stud I65, or I I I, by a suitable tool passed down alongside the stackup, on either side thereof.

When a contact spring ilil or IlI is sufficiently twisted that one of its contact points engages substantially before the other, that fact appears from the observation that one end of the cross head of the spring is stopped before the other. ,A compensating twist can be imparted to the contact spring, preferably near the base thereof, by a suitable tool inserted into the bank alongside the stackup. With respect to the first ten 18 (principal) stackups in a vertical row, the twisting is more readily performed if the tool be inserted along the side of the stackup lying away from the portions I62 (Fig. 15) connecting the contact springs together horizontally, as there is more room on that side for manipulation of the twisting tool. For example, a comparatively large clear space exists for this purpose between the second and third stackups in any vertical row, as Well as between the fourth and fifth, and so on, for the connecting parts I62 for two adjacent stackups lie in the interstackup space immediately following any odd-numbered stackup.

The placing of the contact points of a con tact spring 65 or ill far apart, near the ends of the crosshead, insures reliable twin-contact operation, in that the contact spring twists quite readily to equalize contact pressure if one point is engaged before the other. Also, if a particle of foreign matter physically blocks one contact point from engaging, its mated point nevertheless engages during the over-travel movement because of the twisting compliance of the contact spring.

When a view of the contact points themselves of a single stackup of the bank is desired, a suitab e bifurcate mirror may be used, having parallel arms spaced to straddle the stackup, and respectively narrow enough to enter the free space alongside the springs of the stackup. When the arms of the bifurcate mirror enter the bank endwise a ong a line extending downwardly and to the right at about forty-five degrees from the plane of the bank, the image of the contact points is in view in the arms of the mirror from a position directly above the mirror.

If all the contact points of the bank are to be inspected, a suitable comb-like mirror may be employed which will show a view as above explained of contact points of all stackups in the same vertical row.

P. The hold-pilot sfackups Referring now to Fig. 8, taken along line 88 of Fig. 1, each hold-magnet armature, in addition to the twelve selective stackups comprising the associated vertical row of stackups in the contact bank, has what is termed a holdpilot stackup of contacts, operated each time the hold armature is operated. As shown in Fig. 1, these hold-pilot stackups are supported on the rear portion of cross channels 25, and lie respectively opposite the vertical rows of stackups in they contact bank. They are assembled in a series of pileups clamped by pairs of screws I86. Each hold-pilot stackup contains normally-open contacts (ISI, I82), and an armature-restoring spring H8.

The normally-open hold-pilot contacts of a stackup consist of two fixed contact members MI and their respective contact springs I82. Each such stackup has a lifter stud I83, supported by an actuating tab 33, the free end of which lies on the upwardly offset portion IIJI of the associated hold armatures 90, whereby the hold-pilot contacts are c osed upon the operation of such armature. They may, for example, indicate to a control circuit that the associated hold armature has been operated.

The armature-restoring spring I I8, besides serving to return the associated hold armature Eli) completely to its normal position after operation. holds the top end of actuating stud I83 in position.

Each hold-pilot stackup further contains a pair of inwardly tensioned contact springs 8 normally making electrical contact with each other. The upper spring lo l is slotted longitudinally to receive the upwardly extending stud of control button 235. Such button may beman- 'ually shifted forward underneath the down- Q. Figure 19 Fig. 19 is a. diagrammatic showing of one ex,-

ample of, electrical connections to the switch.

Those stackups of the contact bank which lie in the first, second, and tenth to twelfth horizontal rows are shown for the first, second, and last vertical rows, along with hold-pilot stackups HP, and

hold magnets so for such vertical rows. The encircled numbers I, 2, and iii to 82v identify the horizontal rows,. or the corresponding stackups in a vertical row. Parts Ml, M2,. and M3. to ME 2 are the select magnets for corresponding horizontal rows of stackups.

Each, illustrated vertical row of stackups has a separate set of three-conductors B associated therewith, termed. inlet conductors. Twenty threeconductor outlet sets i to 2c are provided, two for each horizontal row of principal stackups, stackups i to it in any vertical row. Each set of inlet conductors 2% is connected to the terminals I13 of the contact springs of the extension stackups (H and E2) in the concerned vertical row. The three-conductor outlet sets l to Zil'are connected to the terminals no of the horizontal multiple strips Ito, and consequently to the contact springs it! integral therewith.

The six vertical multiple strips I56 in the physical construction are here shown in the manner of wires connecting the fixed contacts of a vertical row of stackups together in multiple, as a mere matter of convenience in the circuit diagram.

, When a. set of inlet conductors Elli! is to be coni nected with one of the sets of outlet conductors l to. ill, the concerned one of the first ten horizontal rows of stackups is selected, along with the; eleventh horizontal row, and the selected stackups are actuated in the vertical row with which the last-named conductors s are associated. The concerned hold magnet to is energized for this purpose, and is held energized as long as the connection is desired. This stackup actuation connects the concerned incoming conductors 2th], through the now-closed contacts of the associated eleventh stackup, the three associated conductors led (the upper three vertical conducting strips E56 ,in the concerned pileup Hit), and the upper three contact pairs of the closed one of the stackups l to It in the vertical row, tothe associated outlet set i to ill. While all six contact pairs in the stack-up last-ment1oned are closed, the closure of the lower three contact pairs isa mere inefiective operation at this time, as the associated conductors i5 6 remain open atthe normally open contacts of the unoperated twelfth stackup.

When the same inlet conductors 2053 are to be connected with one of the sets of oublct All doctors. II to 21!, the operation is the same except that the concerned twelfth stackup is selected and actuated, rather than the eleventh stackup. In this operation, the lower three contact pairs of the actuated principal stackup, and the lower three conducting strips in the pileup 150, are effective rather than the upper three.

Fig. 19 further shows electrical connections for the illustrated hold magnets 8t, hold-pilot contacts HH and 82, and make-busy contacts I84.

The off-normal contact springs 15 associated with the pairs of select magnets, through their selecting shaft, such as S |2, are shown arranged in a typical circuit. To complete such circuit, the contacts l5 associated with the selecting shaft SI l--l 2 and the contacts l5 associated with one of the other five selecting shafts must be closed. The closing of the off-normal contacts 15 may indicate to a circuit, such as a control circuit, that the selecting action has been completed.

II. OPERATION Operation of the disclosed switching arrangementwill now be described.

A. Select-magnet operation As pointed out in connection with Fig. 19,- two selective stackups are required to bc-operated for any connection through the switch, a principal stackup (horizontal rows l to ill) and an extension stackup (horizontal rows i i and, I2),

The selection of the stackupscomprising the first and eleventh horizontal rows (stackups-l and l l in any vertical row), to thereby select outlet conductors i of Fig. 19, will now be described.

Selection of the first horizontal row of stackups occurs responsive'to an, energization of the select, magnet lvil (Figs. 1, 3, 4-, and 19).. The underlying wing 53 of the associated armature 5: is thereby attracted upwardly into, engagement with magnet Ml, whereby the first shaft S l-2 is rotated in a counterclockwise direction as viewed in Fig. l. Thereupon, select. fingers 535 of shaft, Si -2, one for each vertical row of stackups', are tipped forward toward a position underlying horizontal row i. At each idle vertical row of stackups (at which the hold armature Git is in normal position), tipping select finger 5350f shaft Si2v forward acts, through finger springs i375, to rotate the associated selecting lever E25 forwardly about its pivot Hi3 toward an effective position below the first horizontal row. The front offset-side portion 52'? of each such selecting lever H5 is thereupon brought effectively beneath its actuating tab 33 (Fig. 11) of the first horizontal row of staclrups. This preferably occurs, for any lever 25, just as the lever is-about to strike the end of its guide slot ltd. The first stackup is thereby selected in each idle vertical rowin the switch.

The selecting shaft may be arranged (by core adjustment of the select magnets) to rotate through a slightly larger angle than is required for the select levers m5 to reach stop position (at the end of slots lot) to insure that all the selecting levers rotate a sufficient amount. This. excess shaft rotation is permitted by virtue of the inherent flexibility oi the disclosed finger springs. Hit. The concerned driving arms N2 of each finger spring I36 merely yield as soon as the offset side I27 of the selecting lever 25 reaches its. stop position in its slot 890.

If any vertical row of the switch is in use when the selective, action just described occurs, the.

21 raised condition of the actuating channel bar 91 of its hold armature 90 causes the concerned olfset side portion I21 of the selecting lever 25 or such vertical row to strike the side of the con cerned depending actuating tab 33, as may be seen best in Fig. 18. This action prevents such select lever l25 from reaching selecting position. but the full stroke of the select shaft is not thereby interfered with, as the concerned driving arm I32 of the associated finger spring i333 merely flexes as the select shaft completes its movement.

As seen best in Figs. 2 and 4, the abovedescribed rotation of shaft 31-2 tips the attached shaft-positioning roller stud id forward. The roller 59 carried on stud it, is thereby moved toward the front of the switch, from its position at the center of the V-shaped portion at the lower end of cam member 65. Cam member 56 is thereby thrust inwardly against the tension of cam spring 65. When the shaft movement is nearly completed, shaft off-normal springs I5 are brought into engagement by stud 75 carried by cam member 66.

Selection of the eleventh horizontal row (stackup II in any vertical row) is accomplished by energizing the eleventh selecting magnet MII, tc; Igtate shaft SII--I2 as described for shaft S B. Hold-magnet operation Following the above described selecting action of horizontal rows I and I! to thereby select outlet conductors I, Fig. 19, and while the concerned magnets MI and MH are maintained energized, the hold magnet 8i] associated with any idle set of inlet conductors 2% is energized. The depending tractive portion 9| of its hold armature is thereupon attracted downwardly into engagement with the protruding end 84 of the core of magnet 89, rotating the armature structure about the pivotal mounting arrangement hereinbefore described. This action rotates and raises the attached actuating channel bar 91 with all its selecting levers I25. Each such lever i25 passes ineifectively between the associated actuating tabs 33, except in the case of the selected first and eleventh stackups. There, the actuating tabs 33 of the first and eleventh stackups of this bank are raised by the now underlying bridging portions of the first and sixth selecting levers I25. The overlying lifter studs !65 (see Fig. 11) of the first stackup, and the lifter stud H5 (see Fig. of the eleventh stackup are thereby raised, carrying upwardly their contact springs it! and I'll.

When the armature stroke is only partially completed, the contacts carried on the forward end of the flexible springs ltl and I'll encounter those depending from the teeth portion iii? of the respective associated fixed contact strips E55.

The final portion of the movement of the armature causes bowing of the springs iiil and lit, whereby contact pressure is built up at all con cerned points. The hold magnet 38 of the concerned vertical row is maintained energized for C. Select-magnet restoration The energized select magnets (MI and Mi I in the assumed example) may be deenergized immediately following the operation of the hold armature 90. When this occurs, the cam springs and cam members 65 associated with the rollers 89 and roller studs Til attached to the concerned selecting shafts SI-2 and SI I!2 act to return such rollers, studs and selecting shafts to their normal positions. The rollers 59 act re versely in their associated V-notched portions of cam members 66 for this purpose. The normal position of a shaft is reached when its rollers 69 strikes the lowest portion of such notch. Responsive to the return movement of cam 59, the concerned shaft off-normal springs 15 again assume their separated condition illustrated in Fig. 2.

When the selecting shafts Sl-2 and SI ll2 are returned to normal position, their unused selecting levers I25 return with them, but those levers I25 through which the selected stackups in the concerned bank were operated are held in selecting position by the downward pressure exerted by the flexible blades in the actuated stackups. The rear driving arms I32 of the concerned finger springs l3ll remain in selecting position, and fiex as the selecting shafts S I-?. and Si I I 2 return to normal position, while the associated front driving arms I32 return with the shaft.

D. Hold-magnet restoration When the energized hold magnet is subsequently deenergized, the armature thereof rotates back to its normal position by virtue of the weight of the actuating channel bar 9'! thereof, assisted by the downwardly exerted spring tension of the armature-restoring spring H8 (Fig. 8) in the hold-pilot assembly. The tension of the flexible spring contacts in the operated selective stackups assist in the initial portion of the return movement.

When the descending channel bar 9'; is lowered, the first and sixth selecting levers :25 are released from the first and eleventh actuating tabs 33, whereupon the spring action of the rear driving arms I32 of finger springs E35, exerted against the intermediate portion I26 of selecting levers I25, causes the selecting levers to re-align themselves with the finger springs use of the associated shafts SI--2 and SI l-I2, to the position shown in Figs. 5 and 18.

E. Selecting other outlets the lower three conducting strips in the first horizontal row, are to have a connection extended thereto, the selection is the same except that the twelfth rather than the eleventh horizontal row of stackups is selected along with the first horizontal row. This is accomplished by an energization of select magnets Ml and Ml2, to rotate their associated shafts (Si-2, Si I-l2) in the concerned directions. With this selection in effect, energization of any hold magnet as operates its associated hold armature 9% to close the first and twelfth stackups in the associated vertical row. With the twelfth stackup in the concerned vertical closed, rather than the eleventh, 

